Field of the Invention
The present invention relates to a suspension board assembly sheet having circuits, a method of manufacturing the suspension board assembly sheet having circuits, and a method of inspecting the suspension board assembly sheet having circuits.
Description of Related Art
An actuator is used for a drive device such as a hard disc drive device. Such an actuator includes an arm rotatably provided at a rotation shaft and a suspension board having a circuit (hereinafter abbreviated as a suspension board) for a magnetic head attached to the arm. The suspension board is a printed circuit board for positioning the magnetic head at a desired track of a magnetic disc.
The suspension board includes the magnetic head and is connected to another electronic circuit. A conductor trace is formed at the suspension board, and an electrical signal is transmitted between the other electronic circuit and the magnetic head through the conductor trace. The plurality of suspension boards having such a configuration are formed to be integrally supported at a common support frame in the manufacturing process (see JP 2012-18984 A, for example).
In each suspension board, a ground wiring layer (a wiring layer for ground) and a signal wiring layer (a wiring layer for a signal) are formed on a metal support substrate with an insulating layer sandwiched therebetween. The ground wiring layer and the metal support substrate are electrically connected to each other by a via plating portion penetrating the insulating layer. Further, in the support frame, a conductor layer is formed on the metal support substrate with the insulating layer sandwiched therebetween.